You should at least spend a day in Seaside, Oregon. It is on the ocean and very beautiful. You can also see the beach where they filmed Goonies, and where Lewis and Clark stayed. But for sure go to Seaside.
Some great antique shops there too. And it's only a short drive up the coast to Astoria and some GREAT seafood!
I would love to go back there, haven't been to the Oregon Coast in a long time. I drove through Portland a few years ago, but I was on my way to Vancouver.